From: Baoquan He <baoquan.he@linux.dev>
To: linux-mm@kvack.org
Cc: akpm@linux-foundation.org, david@kernel.org, chrisl@kernel.org,
kasong@tencent.com, nphamcs@gmail.com, baohua@kernel.org,
youngjun.park@lge.com, corbet@lwn.net, hannes@cmpxchg.org,
chengming.zhou@linux.dev, kunwu.chan@gmail.com,
klarasmodin@gmail.com, linux-kernel@vger.kernel.org,
Baoquan He <hebaoquan@kylinos.cn>
Subject: [PATCH v5 05/19] mm, swap: widen swap_info_struct max/pages to unsigned long
Date: Mon, 9 Nov 2026 13:54:41 +0800 [thread overview]
Message-ID: <20261109055455.536925-6-baoquan.he@linux.dev> (raw)
In-Reply-To: <20261109055455.536925-1-baoquan.he@linux.dev>
From: Baoquan He <hebaoquan@kylinos.cn>
si->max and si->pages are unsigned int. With 4 KiB pages, this limits
an xswap device to 16 TB. xswap may need a larger address space, so
change both fields to unsigned long.
Several places still use unsigned int for offsets and indexes. Widen
them as well:
- the return value of cluster_offset() and the cluster scan helpers;
- the allocation offsets in cluster_alloc_swap_entry() and
swap_alloc_fast();
- the indexes in find_next_to_unuse() and try_to_unuse().
Also change the related print formats from %u to %lu.
A real swap device is still limited by swap_header.info.last_page,
which is __u32. So this only widens the xswap address space. The old
overflow clamp in read_swap_header() is no longer needed; the header
check still limits real devices.
count_swap_pages() returns unsigned int and is only used by
hibernation. Hibernation never selects an xswap device. If that ever
changes, WARN and return 0 instead of silently truncating the value.
Signed-off-by: Baoquan He <hebaoquan@kylinos.cn>
---
include/linux/swap.h | 4 +--
mm/swapfile.c | 59 +++++++++++++++++++++++---------------------
2 files changed, 33 insertions(+), 30 deletions(-)
diff --git a/include/linux/swap.h b/include/linux/swap.h
index 382a578140b5..569989856c25 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -240,7 +240,7 @@ struct swap_info_struct {
signed short prio; /* swap priority of this type */
struct plist_node list; /* entry in swap_active_head */
signed char type; /* strange name for an index */
- unsigned int max; /* size of this swap device */
+ unsigned long max; /* size of this swap device */
struct swap_cluster_info *cluster_info; /* array, one entry per cluster */
#ifdef CONFIG_XSWAP
struct vm_struct *cluster_vm; /* VM_SPARSE area for cluster_info */
@@ -254,7 +254,7 @@ struct swap_info_struct {
/* list of cluster that contains at least one free slot */
struct list_head frag_clusters[SWAP_NR_ORDERS];
/* list of cluster that are fragmented or contented */
- unsigned int pages; /* total of usable pages of swap */
+ unsigned long pages; /* total of usable pages of swap */
atomic_long_t inuse_pages; /* number of those currently in use */
struct swap_sequential_cluster *global_cluster; /* Use one global cluster for rotating device */
spinlock_t global_cluster_lock; /* Serialize usage of global cluster */
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 00c7b398bafe..83aaf00b75d3 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -429,10 +429,10 @@ static inline unsigned int cluster_index(struct swap_info_struct *si,
return ci - si->cluster_info;
}
-static inline unsigned int cluster_offset(struct swap_info_struct *si,
- struct swap_cluster_info *ci)
+static inline unsigned long cluster_offset(struct swap_info_struct *si,
+ struct swap_cluster_info *ci)
{
- return cluster_index(si, ci) * SWAPFILE_CLUSTER;
+ return (unsigned long)cluster_index(si, ci) * SWAPFILE_CLUSTER;
}
static void swap_cluster_free_table_folio_rcu_cb(struct rcu_head *head)
@@ -836,7 +836,7 @@ static int swap_cluster_setup_bad_slot(struct swap_info_struct *si,
/* si->max may got shrunk by swap swap_activate() */
if (offset >= si->max && !mask) {
- pr_debug("Ignoring bad slot %u (max: %u)\n", offset, si->max);
+ pr_debug("Ignoring bad slot %u (max: %lu)\n", offset, si->max);
return 0;
}
/*
@@ -1002,11 +1002,12 @@ static bool __swap_cluster_alloc_entries(struct swap_info_struct *si,
}
/* Try use a new cluster for current CPU and allocate from it. */
-static unsigned int alloc_swap_scan_cluster(struct swap_info_struct *si,
- struct swap_cluster_info *ci,
- struct folio *folio, unsigned long offset)
+static unsigned long alloc_swap_scan_cluster(struct swap_info_struct *si,
+ struct swap_cluster_info *ci,
+ struct folio *folio,
+ unsigned long offset)
{
- unsigned int next = SWAP_ENTRY_INVALID, found = SWAP_ENTRY_INVALID;
+ unsigned long next = SWAP_ENTRY_INVALID, found = SWAP_ENTRY_INVALID;
unsigned long start = ALIGN_DOWN(offset, SWAPFILE_CLUSTER);
unsigned int order = likely(folio) ? folio_order(folio) : 0;
unsigned long end = start + SWAPFILE_CLUSTER;
@@ -1053,12 +1054,12 @@ static unsigned int alloc_swap_scan_cluster(struct swap_info_struct *si,
return found;
}
-static unsigned int alloc_swap_scan_list(struct swap_info_struct *si,
- struct list_head *list,
- struct folio *folio,
- bool scan_all)
+static unsigned long alloc_swap_scan_list(struct swap_info_struct *si,
+ struct list_head *list,
+ struct folio *folio,
+ bool scan_all)
{
- unsigned int found = SWAP_ENTRY_INVALID;
+ unsigned long found = SWAP_ENTRY_INVALID;
do {
struct swap_cluster_info *ci = isolate_lock_cluster(si, list);
@@ -1141,7 +1142,7 @@ static unsigned long cluster_alloc_swap_entry(struct swap_info_struct *si,
{
struct swap_cluster_info *ci;
unsigned int order = likely(folio) ? folio_order(folio) : 0;
- unsigned int offset = SWAP_ENTRY_INVALID, found = SWAP_ENTRY_INVALID;
+ unsigned long offset = SWAP_ENTRY_INVALID, found = SWAP_ENTRY_INVALID;
/*
* Swapfile is not block device so unable
@@ -1418,7 +1419,7 @@ static bool swap_alloc_fast(struct folio *folio)
unsigned int order = folio_order(folio);
struct swap_cluster_info *ci;
struct swap_info_struct *si;
- unsigned int offset;
+ unsigned long offset;
/*
* Once allocated, swap_info_struct will never be completely freed,
@@ -2509,9 +2510,15 @@ unsigned int count_swap_pages(int type, int free)
spin_lock(&sis->lock);
if (sis->flags & SWP_WRITEOK) {
- n = sis->pages;
- if (free)
- n -= swap_usage_in_pages(sis);
+ /* Hibernation only; it never selects an xswap device. */
+ if (unlikely(sis->flags & SWP_XSWAP)) {
+ WARN_ON_ONCE(1);
+ n = 0;
+ } else {
+ n = sis->pages;
+ if (free)
+ n -= swap_usage_in_pages(sis);
+ }
}
spin_unlock(&sis->lock);
}
@@ -2832,8 +2839,8 @@ static int unuse_mm(struct mm_struct *mm, unsigned int type)
* Return 0 if there are no inuse entries after prev till end of
* the map.
*/
-static unsigned int find_next_to_unuse(struct swap_info_struct *si,
- unsigned int prev)
+static unsigned long find_next_to_unuse(struct swap_info_struct *si,
+ unsigned long prev)
{
struct swap_cluster_info *ci;
unsigned long i, cluster_end, end;
@@ -2903,7 +2910,7 @@ static int try_to_unuse(unsigned int type)
struct swap_info_struct *si = swap_info[type];
struct folio *folio;
swp_entry_t entry;
- unsigned int i;
+ unsigned long i;
if (!swap_usage_in_pages(si))
goto success;
@@ -3722,12 +3729,8 @@ static unsigned long read_swap_header(struct swap_info_struct *si,
pr_warn("Truncating oversized swap area, only using %luk out of %luk\n",
K(maxpages), K(last_page));
}
- if (maxpages > last_page) {
+ if (maxpages > last_page)
maxpages = last_page + 1;
- /* p->max is an unsigned int: don't overflow it */
- if ((unsigned int)maxpages == 0)
- maxpages = UINT_MAX;
- }
if (!maxpages)
return 0;
@@ -4209,7 +4212,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
goto bad_swap_unlock_inode;
}
if (si->pages != si->max - 1) {
- pr_err("swap:%u != (max:%u - 1)\n", si->pages, si->max);
+ pr_err("swap:%lu != (max:%lu - 1)\n", si->pages, si->max);
error = -EINVAL;
goto bad_swap_unlock_inode;
}
@@ -4300,7 +4303,7 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
/* Sets SWP_WRITEOK, resurrect the percpu ref, expose the swap device */
enable_swap_info(si);
- pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s\n",
+ pr_info("Adding %luk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s\n",
K(si->pages), name->name, si->prio, nr_extents,
K((unsigned long long)span),
(si->flags & SWP_SOLIDSTATE) ? "SS" : "",
--
2.54.0
next prev parent reply other threads:[~2026-11-09 5:56 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-09 5:54 [PATCH v5 00/19] mm, swap: extendable swap devices (xswap phase I) Baoquan He
2026-11-09 5:54 ` [PATCH v5 01/19] mm: xswap support for zswap Baoquan He
2026-11-09 5:54 ` [PATCH v5 02/19] mm, swap: refactor free_swap_cluster_info to take swap_info_struct Baoquan He
2026-11-09 5:54 ` [PATCH v5 03/19] mm, swap: add VM_SPARSE cluster-array helpers for xswap Baoquan He
2026-11-09 5:54 ` [PATCH v5 04/19] mm, swap: use a VM_SPARSE cluster array for xswap devices Baoquan He
2026-11-09 5:54 ` Baoquan He [this message]
2026-11-09 5:54 ` [PATCH v5 06/19] mm, swap: add a sysfs interface to create " Baoquan He
2026-11-09 5:54 ` [PATCH v5 07/19] mm, swap: refactor swapoff and add xswap_destroy Baoquan He
2026-11-09 5:54 ` [PATCH v5 08/19] mm, swap: require zswap for xswap devices Baoquan He
2026-11-09 5:54 ` [PATCH v5 09/19] mm, swap: use a stable id " Baoquan He
2026-11-09 5:54 ` [PATCH v5 10/19] mm, swap: let the command line set the xswap device size Baoquan He
2026-11-09 5:54 ` [PATCH v5 11/19] mm, swap: add CONFIG_XSWAP_DEFAULT_MAX Baoquan He
2026-11-09 5:54 ` [PATCH v5 12/19] mm, swap: let swapoff destroy xswap devices by name Baoquan He
2026-11-09 5:54 ` [PATCH v5 13/19] mm, swap: add xswap grow trigger on cluster allocation Baoquan He
2026-11-09 5:54 ` [PATCH v5 14/19] mm, swap: add debugfs counters for xswap Baoquan He
2026-11-09 5:54 ` [PATCH v5 15/19] mm, swap: make xswap cluster_info accesses RCU-safe Baoquan He
2026-11-09 5:54 ` [PATCH v5 16/19] mm, swap: prepare xswap_unmap_clusters for range shrinking Baoquan He
2026-11-09 5:54 ` [PATCH v5 17/19] mm, swap: add xswap shrink trigger and defer it to a workqueue Baoquan He
2026-11-09 5:54 ` [PATCH v5 18/19] mm, swap: do not give an xswap slot to a cgroup that cannot zswap Baoquan He
2026-11-09 5:54 ` [PATCH v5 19/19] mm, swap: skip the overcommit probe when removing xswap Baoquan He
2026-11-09 6:15 ` [PATCH v5 00/19] mm, swap: extendable swap devices (xswap phase I) Baoquan He
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